So I have two games here where I genuinely felt like I had the right strategy for the board and somehow ended up on the losing end of the battle.
I think you were mistaken in strategy in one, but in the second one it was the late-game execution that let you down.
Game 1
Log: http://dominion.isotropic.org/gamelog/201204/23/game-20120423-230637-242f2e3a.html
Surveying the board I don't really like too much of it so I decide to go a little shanty town smithy with some money backup to get an expand. Then draw most of my deck play an expand for a better VP (Grab a duchy or a province ideally) and buy a province.
My initial thoughts looking on this log was that maybe I undervalued salvager?
Looking at your comments, my thoughts are:
1) Village+Smithy+Money isn't as good as just Smithy+Money, unless you have some good reason to make an engine.
2) Shanty town isn't that great when used as a traditional village in a Village+Smithy engine. So you need a REALLY good reason to be buying shanty towns and smithies to make an engine.
So if you're building a Shanty Town/Smithy engine, you should have some darn good reason, and I don't think a single expand was good enough. Also, for an engine, +buy is important, and you skipped Salvager, which is both early trashing AND the only +buy on the board.
Most critically, you missed a textbook combo - "Peddler" combos with "Trash for benefit". You can buy peddlers for cheap after playing a bunch of actions, then trash them for $8 with Salvagers. (Or, in general, would also work with Remodeling them into Provinces, Expanding into Colonies, Upgrading into Platinums, etc.)
Your opponent went for a similar engine, but instead of the payload being money, the payload was peddlers, which made his engine more consistent. Of his five provinces, three were bought by Salvagers trashing Peddlers.
Game 2
Log: http://dominion.isotropic.org/gamelog/201204/24/game-20120424-000048-b1112d31.html
Here I play Standard Double Tac+Black Market engine with one wharf while he plays Alchemists and one wharf. The game ends on my turn 14 (I went second) with me 2 points behind from a duchy purchase on his turn 13. (I bought an estate on the last turn because I couldn't afford province duchy and had previously whiffed tactician so my hand was smaller than normal). This game more so than the first I can't see anything I did glaringly wrong. Were my black market purchases no good (torturer for draw, highway for cost reduction/cantrip). Was it because I had second player disadvantage? Was it bad draws?
Note all constructive criticism is greatly welcomed. Thanks in advance for the advice and your time.
For this one, I'm going to point out the last turn of the game. You just didn't keep track of the points. You could have won if you went double-duchy instead of province-estate.
Especially since you had a functioning double-tactician deck. You had just discarded three to cards to tactician, you would have started the NEXT turn with a 10-card hand. Your opponent, on the other hand, had just broken their alchemist chain! They didn't draw their potion, didn't return their alchemists to the top! They only had enough to buy a Duchy! And yet you bought province-estate and ended the game with a loss. You should have bought two duchies, and then been in excellent shape, since your engine was still going whereas his had already collapsed.